A light-detection technique may count individual photons to measure intensity of light (e.g., a single photon counting (SPC) technique). For example, incident photons may be counted individually over a period of time to obtain a measurement of light intensity and/or flux during an imaging operation.
A delay (e.g., a dead-time) may be created after a photon is received until a circuit (e.g., a light-detection circuit) is ready to receive another photon. The delay may limit an upper photon count rate, making the light-detection technique unsuitable in an application requiring high-speed processing and/or high dynamic range imaging (e.g., a biomedical application, a military application, a nighttime imaging operation, a low light imaging operation).
Reducing the delay using faster transistors may result in increase of a dark count (noise) due to an afterpulsing effect. A reduction of the delay through operating the circuit at a low bias voltage may decrease a probability of detecting a photon detection of the circuit. A decrease in the probability of detecting the photon may reduce the sensitivity of the circuit. A decrease in sensitivity may lead to an inaccuracy in photon count. Consequently, the light detection circuit may not perform efficiently in high sensitivity and high speed applications.